A base station antenna usually adopts a form in which elements form an array, to form electromagnetic wave beams having a higher gain and meeting a certain shape requirement to transfer a wireless communication signal. Presently, the base station antenna equipped with more elements becomes the mainstream gradually, particularly the intelligence antenna of Time Division Synchronized Code Division Multiple Access (TD-SCDMA) and the Multiple-Input Multiple-Output (MIMO) antenna of the Long Term Evolution (LTE) system, in which not only an array is formed in the vertical surface of the antenna, but also multiple columns of antenna arrays are needed to be formed in the horizontal surface.
The base station array antenna has many elements therein, when a certain antenna element can not work normally due to certain reason (such as short circuit or open circuit of feed), a reflection coefficient of the main port of the array will not generally deteriorate seriously, therefore, the base station will not send a standing wave alarm. However, the array pattern will be influenced obviously, for example a lobe pattern is not enough symmetrical, the side lobe suppression is poor, and the gain reduces and so on.
The prior art provides a standing wave monitoring circuit for monitoring a standing wave ratio of a base station antenna-feeder system and outputting different levels of alarm signals and a standing wave monitoring method based on the circuit. However, the circuit design for the monitoring method is complicated, the object to be monitored is a radio frequency signal at the junction between an antenna-feeder and a radio frequency terminal device, and the standing wave situation of the elements within the base station antenna can not be detected.
In summary, in the prior art, only the radio frequency signal between the radio frequency front-end circuit and the antenna-feeder port is monitored, different levels of alarm signals are sent when the standing wave of the radio frequency signal is abnormal. However, for a large antenna array, when an individual element within the antenna has abnormal situation, such as rosin joint, short circuit, or the mechanical structure of the element being broken, the standing wave of the radio frequency signal at the junction between the antenna-feeder and the radio frequency front-end circuit will not appear to be abnormal obviously, hence the abnormal situation of the element within the antenna array can not be detected.